Last week British Airways announced that the world’s first sustainable aviation fuel plant will be built in Thurrock, Essex. The airline claims that 575,000 tonnes of plastic waste, otherwise destined for landfill or incineration, will be converted into 120,000 tonnes of liquid fuel each year. According to BA, that’s enough to power the annual flights from London City Airport, twice over. The concept of converting landfill waste into jet fuel sounds like something out of a science fiction film, but in fact, relies on two long-standing techniques.
From landfill to jet fuel: could plastic pyrolysis reduce our reliance on fossil fuels? Photo credit: (L) David Dodge, (R) Flickr user Eddie.
So just how does it work? British Airway’s partner, the US-based biofuels firm Solena, is planning to implement a three-step process at the Thurrock plant. The first stage invokes a process called pyrolysis (derived from Greek pyro [fire] and lysis [loosening or separation]), which involves the decomposition of organic material at high temperatures. The key difference from combustion is that in pyrolysis, heating is conducted in the absence of oxygen, leading to the production of gases such as carbon monoxide, hydrogen and methane (as opposed to CO2). For plastic pyrolysis, gasification is achieved using a high temperature plasma arc at 4,000 – 5,000ºC.
Pyrolysis can occur when lavas flows come into contact with vegetation. This photo depicts the aftermath of a fissure eruption on Kīlauea, Hawaii, in 1983. Photo credit: USGS
The second key stage in the production of biofuel harnesses a series of chemical reactions, which were first defined in the 1920s as the Fischer-Tropsch process, to transform the carbon monoxide and hydrogen gas into light hydrocarbons. A third and final step upgrades these hydrocarbons into high-grade jet fuel.
Perhaps the most exciting aspect of this technology is it that in addition to the liquid biofuel, the high temperature treatment of plastics produces enough synthetic gas to power the entire pyrolysis plant. It is, in effect, a self-sufficient exercise. The chosen site in Thurrock is a former oil refinery, thus the infrastructure for transport and storage of fuel already exists.
One additional attraction of plastic pyrolysis is that the leftover carbon is stored in a stable solid residue, called ‘biochar’, which can be applied to soil to improve its structure and fertility. Photo credit: Lou Gould.
The climbing cost of landfill tax makes the construction of a plastics pyrolysis plant increasingly financially viable. In fact, British Airways has committed to purchasing the jet fuel produced by the plant for the next 11 years, a contract that equates to a total of roughly $550 million. Similar projects are planned for other countries, with American Airlines being keen to follow suit.
If all this seems too good to be true, then maybe it is. Before we all get too excited about jetting off on guilt-free long haul flights, we shouldn’t forget the first of the three Rs: Reduction.
The raw material for the pyrolysis (known as feedstock) is waste that cannot otherwise be recycled, for example plastics screenings from food recycling, contaminated paper-plastic mixes and old tyres. Production of all of these waste streams consumes vast amounts of fossil fuels and finite raw materials, and similar investment efforts should focus on trying to minimize the volumes we use in everyday life.
Furthermore, this news should not diminish attempts to reduce reliance on aviation as a method of transportation, particularly short distance flights. The type of technology detailed here could just as easily be used to produce biofuels for use in various forms of public transport. And although BA is keen to promote its green credentials by using a sustainable replacement for liquid kerosene, it should be remembered that the predicted annual usage of 120,000 tonnes of biofuel represents <2% of their annual fuel consumption.
A small step in the right direction.
